Let \(R\)  be an associative ring with identity. We denote the category of left \(R\) -modules by \(\textrm {Mod}R\) . Assume that \(({X},{Y})\)  is a cotorsion pair in \(\textrm {Mod}R\) , that is \({Y}=\lbrace M:\mbox{Ext}^1_R(X,M)=0\mbox{ for every } X\in {X}\rbrace \)  and \({X}=\lbrace N:\mbox{Ext}^1_R(N,Y)=0\mbox{ for every } Y\in {Y}\rbrace \) . We introduce the following classes, which comes from [1]}:
